Throughout this application various publications are referenced in parenthesis. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.
Ginkgo biloba fruits and seeds have been long used in Chinese folk medicine. The first mentioning of such a use appeared in the book of Liu Wen-Tai in 1505 in China. In the 1960""s the structures of the active components have been analyzed. Around the same time, in 1965 the first leaf preparations were placed in modern medicine by the Willmar Schwabe AG, Germany. In 1971 after a collaboration between the Willmar Schwabe AG, Germany and the Beuafour group (IPSEN) in France the first concentrated and standardized extract EGb761 (Germany 1971: DE 2117429 C3 and France 1972: 72.12288) were launched and commercialized as Tanakan (France) and Tebonin Forte (Germany). Following the European application, in 1977 a leaf extract was described in the Medical Dictionary of the Republic of China. During the next decade other companies also placed similar products on the market. Today, Ginkgo biloba leaf extracts are found in several kinds of products, such as food supplements and energy pills, homeopathic uses, juices, cosmetics, various tea preparation, cigarettes, Ginkgo wine or and even in potato snacks referred to as the xe2x80x98memory snackxe2x80x99. The biological activities from the extracts are diverse and known to be effective in: increasing short-term memory, treatment of cerebral insufficiency and dementia, beneficial effects as an antiasthmatic and against polyuria or tinitus, PAF-inhibitor and improving the blood flow, vaso-protection and radical scavenging.
Since the current extract Egb761 contains only between 5-7% of this terpene trilactones, the extract is only used as a food and health supplement. In order to further enhance the market for Ginkgo biloba products, the interest is geared towards extracts with higher purity. In contrast to the large number of patents, where the extraction procedure is rather complicated or the terpene trilactones can only be obtained in a low purity, disclosed herein is a simple extraction procedure for producing a terpene trilactones concentration that is 10-fold higher. Disclosed is a method of isolation and concentration of the terpene trilactones from leaves of the tree Ginkgo biloba or from pharmaceutical powder can be used on the industrial scale.
Disclosed is a method of isolating terpene trilactones from Ginkgo biloba plant material or extract comprising the steps of suspending the plant material or extract in either water or an aqueous solution of an oxidation reagent; extracting the terpene trilactones using an acceptable extraction agent; separating the organic layer from the aqueous layer; washing the organic layer with an acceptable aqueous salt solution, which may be an alkaline solution; and drying the organic layer to form a dried extract containing terpene trilactones. Further processing by reversed phase chromatography of the extracts with polymeric resins reduces the level of undesirable ginkgolic acids to amounts less than 10 ppm.